1. Field of the Invention
The present invention relates to a vehicular lamp, and more particularly to a seal structure provided between a seal groove formed on a lamp body of the vehicular lamp and a leg part of a front lens fit on the seal groove, and process for providing the same.
2. Conventional Arts
As a seal structure between a leg part of a front lens and a seal groove for a vehicular lamp, there has been widely known a structure in which a hot melt material as a seal member is applied to the seal groove, and then the leg part of the front lens is fitted into the seal groove so that the leg part of the lens and the seal groove are sealed together by the hardened hot melt material.
However, the conventional seal structure employing the hot melt material as mentioned above suffers from a problem that since the hardened hot melt material has a strong adhesive strength it is difficult to strip off, at a later date, the front lens from the seal groove if someone wants to exchange only one of the lamp body and the front lens. Therefore, the lamp body as well as the front lens must have been exchanged together as one unit. For this reason, for example, when the automobile is scrapped the lens cannot be used again for a new car even if the front lens has no damage. On the other hand, if a front lens is broken by a hit of a small stone while driving the car, not only a new front lens but also the lamp body must be exchanged even if the latter is still new. In other words, no recycling has been available with the conventional seal structure. In the past, so many scrapped automobiles have caused environmental disruptions because of the industrial waste which requires much spaces as a dumping ground. The recent strong demand is to recycle parts of the automobiles to new cars. With respect to front lens and lamp bodies of vehicular lamps, the conventional seal structure cannot satisfy such a demand because these parts cannot be separated from each other.
Further, the conventional seal structure also suffers from a difficulty that a shrinkage occurred when the hot melt material hardens causes a gap between the seal groove and the hot melt material, which deteriorates waterproofing efficiency.
In view of the foregoing difficulties, there have been proposed improved seal structures capable of recycling lamp parts by separating a front lens from a seal groove of a lamp body if required. One example of such a structure is as disclosed in Unexamined Japanese Utility Model Application No. Hei. 1-83202. This structure employs, as shown in FIG. 1, an elastic member 3 which is unitarily formed with an end portion of a leg part 2 of a lens body 1. The elastic member 3 acts as a packing member for engaging the leg part 2 with a housing of the lamp body. With this structure, since the packing member 3 is unitarily formed with the leg part 2 previously the leg part 2 of the lens 1 can be assembled onto a seal groove 4 by merely engaging the leg part 2 of the lens 1 with the seal groove 4.
With the first proposed structure as disclosed in Unexamined Japanese Utility Model Application (OPI) No. Hei. 1-83202 and shown in FIG. 1, however, since the packing member 3 has a size enough to sufficiently pressure-fitted into the seal groove 4 to accomplish the sufficient waterproof between the packing member 3 and the seal groove 4, it is difficult during assembly to engage the packing member 3 integrally formed with the leg part 2 of the lens 1 with the seal groove 4.
There has been proposed another type of the improved seal structure as disclosed in Unexamined Japanese Utility Model Application (OPI) No. Hei. 2-123010. In this structure, as shown in FIG. 2, a hollow packing member 5 is first fixed in a seal groove 4, and then a leg part 2 of a lens 1 comes into engagement with the seal groove 4 from a top of the packing member 5 thereby to maintain a compressed condition of the hollow packing member 5. The leg part 2 is provided with a protrusion 2a extending radially outward thereof and engaging with an opening 4c disposed on a side wall of the seal groove 4 to accomplish a mechanical engagement between the lens 1 and the lamp body.
However, in the structure as disclosed in Unexamined Japanese Utility Model Application (OPI) No. Hei. 2-123010 and shown in FIG. 2, although it may be easy to insert the hollow packing member 5 in the seal groove 4, the packing member 5 may be fitted eccentrically toward one of side walls 4a and 4b of the seal groove 4. Therefore, it is not easy to achieve a uniform sealing pressure along the entire direction of the seal groove 4, which would suffer from a problem in deteriorating the sealability.